With the advent of electronic fuel control systems for internal combustion engines, a sensor for detecting the quantity of air being inhaled by the engine is required. This information is required by the electronic fuel control system to accurately control the quantity of fuel to be delivered to the engine. Mass air flow sensors have been developed to directly measure the mass air flow rate of the air through the engine's air flow. The mass air flow sensor must not only accurately measure the mass air flow rate through the engine's air intake manifold, but also must be able to quickly respond to rapid or step changes in the engine's air intake manifold in order to assure a proper quantity of fuel is being delivered to the engine. If the response time of the mass air flow sensor is too long, too much, or too little, fuel may be provided to the engine.
During rapid acceleration of an automotive vehicle, the operator will rapidly open the engine's throttle causing a step change in the mass air flow rate through the air intake manifold. As is known in the art, an acceleration enrichment portion of the electronic fuel control system will momentarily increase the quantity of fuel being delivered to the engine. This increase automatically compensates for time lag between the step increase in the quantity of air being delivered and quantity of fuel being delivered under the control of the electronic fuel control system.
Since the quantity of air being delivered to the engine is one of the primary factors used in the computation of the quantity of fuel to be delivered, it is imperative that the response time of the mass air flow sensor be sufficiently short so as not to significantly contribute to the lag between the step increase of the quantity of air being delivered to the engine and the delivery of a corresponding increased quantity of fuel.
As part of the normal production quality control process, the response time of the mass air flow sensor is tested to determine if it is within specification limits.
The invention is an automated response time apparatus which is fast, accurate and highly repeatable.